Why is ESPN's US Open coverage starting later than USA's?

Their daily coverage of the tournament will be starting at 1PM, which is two hours later than the 11AM start that USA always had. Now, a lot of people might be thinking I'm just being greedy. After all, ESPN's coverage (actually, ESPN2's coverage) will run every day from 1PM to 6PM, and then again from 7PM to past midnight (whenever the late match ends). And even that hour between 6 and 7PM is going to be filled with a scoreboard/highlights show, so they're going to have almost nonstop coverage from 1PM to 11PM and even later.